Don't ever retype your code when posting. We need to see the exact code you are trying to read. Don't you think that it is way faster to do a copy/paste than to sit and retype text?

And as noted by Kai - your multimeter is intended to read static signals. It is not fast enough to pick up short pulses. The best way to view the signals is with an oscilloscope. But there are also cheap logic probes that can be used. They normally have a feature to light a LED even for a short pulse.

The good way to test the electrical parts is to try to modify the firmware to run everything as slow as possible. An infinite loop directly before - or after - the readout of the ADC value, but before you restore the state of the /RD and /CS signals will keep the ADC constantly driving the data lines and make it easier for you to use a multimeter. It will also allow you to verify that the low state of the /RD and /CS is really reaching the ADC. If you have another processor pin free, then you can create a wait function that you can insert at different positions in the code, and that waits until you press a button coneected to that spare pin - just notice that such a concept requires you to create a little debounce logic, to avoid getting a single button press to be registered as multiple presses.